Second-Hand Smoke Tenth Biggest Risk Factor For Cancer, Study Finds

The study analyzed 34 risk factors ranging from exposure to pollution to diet constitution, to come to its findings.

2 min read

If you live with someone who smokes tobacco, you may have a much higher risk of getting cancer, a new study found.

A study published in The Lancet states that second-hand smoke is the tenth biggest risk factor for cancer.

The study, done by researchers at the University of Washington, uses a combination of data from the Global Burden of Diseases, Injuries, and Risk Factors study published in 2019, and other risk factors to identify the causes of cancer.

The study analyzed 34 risk factors - environmental, occupational, behavioural, and metabolic - to identify the most common causes of over 23 types of cancer and cancer-related death.

The study also scrutinized changes in the cancer burden between 2010 and 2019 from different risk factors.


Cancer burden and risk were estimated based on mortality and disability-adjusted life-years (DALYs), i.e., a measure of years of life lost to death and years lived with disability.

The study assumed that all persons living with a daily smoker are exposed to tobacco smoke and used employment surveys to estimate the proportion of individuals exposed to secondhand smoke at work.

Second-hand smoke is smoke from burning tobacco products, like cigarettes, cigars, hookahs, or pipes. Secondhand smoke also is smoke that has been exhaled, or breathed out, by the person smoking.

People may also be exposed to secondhand smoke in public places like bars, restaurants, and casinos, as well as in vehicles.

Alcohol, Smoking, and Obesity - The Deadly Trifecta

The study found that smoking, alcohol use, and high body mass index (BMI), were the top three risk factors for cancer. These were followed by unsafe sex, high fasting blood glucose, particle air pollution, asbestos exposure, diets low in whole grains and milk, and second-hand smoking.

These factors accounted for 3.7 million deaths and 87.8 million disability-adjusted life-years in 2019, the researchers said.

"This study illustrates that the burden of cancer remains an important public health challenge that is growing in magnitude around the world. Smoking continues to be the leading risk factor for cancer globally, with other substantial contributors to cancer burden varying."
Christopher Murray, Director, Institute for Health Metrics and Evaluation, University of Washington.

According to the US Centers for Disease Control and Prevention (CDC), there are more than 7,000 chemicals in tobacco smoke, including hundreds of chemicals that are toxic and about 70 that can cause cancer.

“Secondhand smoke can cause health problems in children and adults, and can even be deadly. Since 1964, about 2,500,000 people who do not smoke have died from health problems caused by secondhand smoke exposure,” the CDC states.

Check out this infographic on what happens when you keep smoking tobacco.

The study analyzed 34 risk factors ranging from exposure to pollution to diet constitution, to come to its findings.

This infographic shows what happens to the body as you keep smoking tobacco.

(Infographic: Deeksha Malhotra/FIT)

(With inputs from PTI)

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